Fuse holder



Nov, 10, 1942.

L.. PIERCE ET AL FU SE HOLDERS Filed April 2'7, 1940 INVENORS Lawrerzae Pierce, Job/2 M .SfliflZE/[US and Margy? 14 127611.

Patented Nov. 10, 1942 FUSE HOLDER Lawrence Pierce, E'dgewood, John W. Samzelius, Forest Hills, and Martin Wibell, Wilkinsburg,

assignors to Westinghouse Electric &

Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application April 27, 1940, Serial No. 332,046

14 Claims. (Cl. 200-134) Our invention relates generally to fuse holders, and more particularly to fuse holders adapted to positively clamp a fuse terminal in relatively high pressure engagement.

Heretofore, fuse holders have, in general, been of two general types, that is, the clamp type and clip type. The clip type of holder, in general, comprises a generally U-shaped resilient clip for receiving a fuse terminal. However, it has been found impractical to obtain high contact pressures with this type of clip because it then becomes exceedingly difficult to insert the fuse in the holder. The clamp type of holders used heretofore have been mere clamps, and because the special conditions to which fuse holders are subjected were ignored, such prior clamp holders have proven generally unsuccessful in service.

Accordingly, one object of our invention is to provide a novel type of fuse holder of relatively simple form, but which is capable of efilciently providing high pressure contact with respect to a fuse terminal over long periods of time.

As stated above, fuse holders are subjected to certain special conditions and have certain special requirements which must be taken into consideration in the provision of a practical type of holder. These holders, must in addition to providing a high pressure contact with the fuse clip, be capable of conducting relatively high values of electric current, and at the same time have some resiliency to take care of frequent expansions and contractions caused by self-generated heat and heat transmitted thereto from the fuse proper.

Another object of our invention therefore, is to provide a novel type of high pressure fuse terminal clamp which is capable of conducting relatively large electric currents, and maintaining such high pressure under all conditions.

Another object of our invention is to provide a novel high pressure fuse clamp having a low resistance but of a high mechanical strength.

Another object of our invention is to provide a novel fuse clamping device having cooperating clamping jaws, at least one of which is of a good electrical conducting material, with means relieving or neutralizing the strain on said one aw.

Still another object of our invention is to provide a fuse clamp having cooperating clamping jaws at least one of which is of a good electrical conducting material, with novel means for reinforcing said one jaw.

Another object of our invention is to provide 55 a fuse clamp of the type described with means for limiting relative longitudinal movement of a fuse.

These and other objects of our invention will become more apparent upon consideration of the following detailed description of preferred emmodiments thereof, taken in connection with the attached drawing, in which:

Figure 1 is an end elevational view of a preferred form of fuse terminal clamp with portions of the support therefor in section;

Fig. 2 is a view similar to Fig. 1 but showing the clamp in a released position;

Fig. 3 is a top view of the fuse clamp shown in Figs. 1 and 2 and illustrating a portion of a fuse cooperating therewith;

Fig. 4 is a view similar to Fig. l of a modified form of fuse clamp adapted for use with another type of fuse;

Fig. 5 is a side view of a portion of a fuse se cured in a clamp like that shown in Fig. 4; and

Fig. 6 is an end elevational view partially in section illustrating a modified form of fuse clamp for use with a fuse having a blade type of terminal.

Referring to the drawing, and particularly to Figs. 1 to 3 thereof, we have shown a fuse 2 hav-- ing a blade type of end terminal 4. For conductively connecting a fuse having this type of terminal in a circuit, we prefer to use a clamp of the type shown in Figs. 1 to 3 which includes a conducting jaw member 6, which may be made of any suitable conducting material, such, for example, as copper or the like. The conducting j aw 6 is adapted to cooperate with a clamping jaw 8 which may be of a substantially rigid material or of a resilient material, such, for example, as spring steel. As shown, the clamping jaw 8 is substantially right angular in form and includes a clamping jaw portion I0 and a base portion I2 extending substantially at right angles to the jaw portion 10. Similarly, the conducting jaw member 6 is provided with a jaw portion M which, in the clamping position, normally lies substantially parallel to the clamping jaw portion Ill.

The conducting jaw 6 further includes a base portion l6, which, as shown in Fig. 2, normally lies at an angle somewhat greater than 90 with respect to the jaw portion I l. The jaw M of the conducting jaw member 6 is provided at a point spaced from the base portion I6 thereof with a substantially centrally located rectangular aperture It for receiving a portion of the base 12, of the clamping jaw member 8. As is apparent from Fig. 3,

the base portion ii of the jaw member 8 is enlarged at the outer end thereof to form opposite shoulders 20, for engaging the outer side of the jaw portion 24 of the conducting jaw member 6, to prevent movement of the clamping jaw member 8 away from the jaw member 6. The aperture i8 is preferably somewhat larger in dimensions than the cross section of the base portion l2 of the clamping jaw member 8, so as to permit free pivotal movement of the jaw member 8 in the aperture it. Most good conducting materials, such as copper or the like, if properly proportioned to form the conducting body 6 with respect to current requirements, would not be strong enough to withstand the high clamping pressures, and if designed of a sufficiently large cross section to withstand such pressures would then be entirely too large and bulky to conform to the space requirements, particularly where fuses are enclosed in metal or other containers. In view of this, we have provided a reenforcing strip 22 of relatively stiff, resilient material, such, for example, as spring steel, which strip has a shape conforming to the jaw member 8 and is adapted to be positioned in intimate engagement therewith, as shown in Figs. 1 to 3. The reinforcing strip 22 an the adjacent portion it of the conducting jaw member 6 are provided with aligned apertures for receiving a mounting bolt 24, with a conducting terminal strip 23 secured between the base It and an insulating support 28. As shown, the bolt 24 passes through the insulating support 23, terminal strip 28, base 16 of the conducting jaw 6, reenforcing strip 22, and is provided with a washer and a nut 30 for securing these parts rigidly to the support 28. The base portion l2 of the clamping jaw member 8 is also provided with an aperture 32 aligned with the aperture in jaw 6 for bolt 24, with the aperture 32 somewhat larger than the bolt 24, for freely receiving the outer end of the bolt; and a clamp nut 34, threadedly engaged with the outer end of the bolt is provided for controllin the pivotal movement of the clamping jaw 8 in the aperture is. As shown in Fig. 3, the terminal strip 25 is adapted to be connected to a line conductor 35, as by means of a screw 38 or the like.

As mentioned above, the clamp is shown in Fig. 2 in a loosened condition, and in this position the blade terminal 4 of the fuse 2 may be inserted between the jaw portions l5 and I4, whereupon the clamping nut 34 can be tightened. Th high pressure exerted by the jaw portions I and I4 by tightening of clamp bolt 34, bends jaw portion E4 to the right, as viewed in Figs. 1 and 2, at the same time bending and stressing the resilient backing member 22, which is of a material strong enough to give a very high contact pressure between the fuse blade terminal 4 and the conductor jaw 6. Any heating and cooling of the clamp induced by varying loads in the circuit which may cause heating and cooling of the jaw or fuse. and consequent expansion and contraction of the jaw members 6 and 8, will be taken up by the resilient backing member 22 and, therefore, substantially constant high contact pressure is maintained even though the conducting jaw and terminal strip 26 become annealed dead soft. ihe removal of the fuse is simply and easily accor plished merely by completely loosening the clamping nut 34 and the clamping jaw member 8.

It can be seen from the above described structure that we have provided, a clamping device for a fuse terminal of the blade type which establishes a good electrical connection'by way of the conducting jaw member 6, under high pressures exerted by the clamping nut 34, and wherein the conducting parts, particularly the conducting jaw member 6, is reenforced by the resilient reenforcing strip 22 so that this part is not called upon to take any of the strain of the high pressure contact. On the other hand, none of the parts which do take the strain of the high pressure contact are required to carry any current inasmuch as these parts are of a relatively higher resistance than the conducting jaw member 6 and, therefore, these parts are relatively unaffected by varying load conditions in the circuit in which the fuse is connected.

In Figs. 4 and 5 of the drawing, we have shown a clamp embodying the general principles of the clamp shown in Figs. 1 to 3 and which is especially constructed for use with a fuse having a terminal cap of generally circular form. Inasmuch as some of the parts shown in Figs. 4 and 5 are substantially the same as those shown in Figs. 1 to 3, like reference numerals will be used to designate like parts. The fuse shown in Figs. 4 and 5 is provided with a terminal cap 40 having a cylindrical flange, and for clamping this type of terminal in a circuit, we have illustrated a conducting jaw member 42 of suitable conducting material, such, for example, as copper or the like, and a clamping jaw member 44 which may be either rigid or of a spring steel. The conducting jaw member 42 is provided with a base portion 45 adapted to be seated on the insulating base 28, and a laterally, upwardly extending portion terminating an arcuate outer end 48 of substantially the same curvature as the fuse terminal cap 40. The clamping jaw member 44 is provided with a relatively wide base portion 49 and a relatively narrow arcuate outer end 53 for engaging the fuse terminal cap 40. The upright portion of the conducting jaw member 42 is provided with an aperture somewhat larger than the narrow outer end portion of the-clamping jaw 44 but smaller than the wider base portion thereof, so that the outer end portion 53 of the clamping jaw member 44 may be assembled with respect to the conducting jaw member 42 by being inserted through the aperture 4! in the conducting jaw member until the shoulders formed at the junction of the wide and narrow portions of the clamping jaw 44 abut against the side of the conducting jaw member 42. The conducting jaw member 42 adjacent the lower portion of the arcuate portion 48 thereof is provided with a lateral side extension 59 of limited extent, which includes an inwardly struck portion 52 positioned to engage the end of the fuse terminal cap 49 to limit endwise, longitudinal movement of the fuse with respect to the clamping device. The conducting jaw member 42, similarly to the conducting jaw member E shown in Figs. 1 to 3, is provided with a spring steel reenforcing strip 54 generally conforming in shape to the shape of the conducting jaw member 42, and a bolt 24 is also provided in this embodiment of our invention for securing the conducting jaw member 42, resilient backing strip 54 and terminal strip 26 to the insulating base 28 by means of a nut 3-5. The base portion 49 of the clamping jaw member 44 is also apertured to receive the outer end of the bolt 24 and a cap nut 55 is provided for controlling the pivotal movement of the'clamping jaw member 44 in the aperture 41 i the conducting jaw member 42. The resilient backing strip 54 for the conducting jaw is, of course, provided with an aperture aligned'with the aperture 41 in the conducting jaw member .2 for receiving the clamping jaw member 44. As seen in Fig. 5, the resilient backing strip 54 and conducting jaw member 42 are provided with aligned, longitudinally elongated, central apertures 58 therethrough for accommodating the cap nut 56 when it is tightened to exert a high pressure contact between the clamping jaws and the fuse terminal cap 40.

The operation of the clamp shown in Figs. 4 and 5 is similar to that shown in the embodiment of Figs. 1 to 3, and hence, will not be described in detail. The clamp is shown'in Fig. 4 as in a clamping condition, and normally, when released, the conducting jaw member 42 and its resilient backing strip 54 are adapted to lie in a. position somewhat to the right of that shown in Fig. 4 having an initial set similar to the conducting jaw 6 and the resilient strip 22, shown in Fig. 2 of the drawing. When the cap nut 56 is tightened to move the base portion 49 of the clamping jaw member 44 downwardly, causing it to fulcrum in the aperture 41, the curved outer end 53 thereof is moved towards the conducting jaw member 48 and causes this jaw member and the spring backing strip 54 to move somewhat toward the left, as viewed in Fig. 4 to provide a high contact pressure between the fuse terminal cap 40 and the conducting and clamping jaw members. The slight movement of the resilient strip 54 and conducting jaw portion 48- toward the left when pressure is applied to the clamps shown in Fig. 4, is permitted by the apertures 58 in these members which receive the.

cap nut 56.

In' Fig. 6, we have shown a modified form of clamp for use particularly with a fuse having a blade type of terminal but the general principles of which obviously may be used with any type of fuse terminal, as with the general type of clamp shown in Figs. 1 to 5. This embodiment of our invention is intended to provide substantially the same functions as the clamps heretofore described, without the necessity of using a resilient backing strip for the conducting jaw member. Here again, like reference numerals are used to designate like parts. As shown, the clamp of Fig. 6 includes a conducting jaw member 6!! having a, substantially right angularly disposed base portion 62 suitably apertured to be secured to the base 28 by the bolt 24. The outer end of the conducting jaw member 6!] is provided with an angularly disposed part 64 having an aperture therethrough for freely receiving the clamping screw 66. The conducting jawmember 60 isprovided with enlarged aperture 63 therethrough for receiving the reduced outer end portion of a clamping jaw member 1E]. The jaw 19 is provided with a base portion 72 and an angularly disposed, arcuate clamping portion 14 for engaging the fuse terminal 4. The base portion 12 of the clamping jaw is provided with a socket T6 for receiving the outer end of the clamping screw 66 and the screw in turn is provided with a square nut 73 located close enough to the jaw member to prevent turning of the nut when the screw 66 is turned to move clamping jaw Hi relative to the conducting jaw member Be. The screw 66 also acts as a brace for the conducting jaw member 60 by virtue of the reaction of nut 18 against the bent upper end 64 of the conducting jaw member 60. This produces a counter-clockwise moment against the clockwise moment of the clamping portion 1'4 of. the'clamping jaw 10. This bracing is an important feature inasmuch as it prevents bending of the conducting jaw member 60 which, like the conducting jaws in the previously described embodiments, may be of relatively soft material which is a good conductor such as copper or the like. As pointed out before, this bracing is necessary because if the conducting jaw (50 is dimensioned for current rating alone, it will, in general, be too weak to stand the clamping pressure. Furthermore, the relatively large rectangular opening 68 through the conducting jaw member 60 further reduces the strength of the jaw, so that if the jaw were dimensioned to withstand the clamping pressure, it would be entirely too large to comply with the dimensional requirements of fuses of this character, particularly those which are enclosed in metal or other housings. By making the clamping screw 66 slightly inclined with respect to the vertical clamping surfaces, as shown in Fig. 6, it is possible to place the fulcrum for the clamping jaw 19 substantially at one corner of the aperture 68 and thus obtain maximum lever ratio for the clamping action. The base 12 of the clamping jaw member 13 being provided with a socket W for receiving the end of the clamping screw 66, thus provides a simple joint that will maintain an almost constant lever ratio over the entire clamping range. To maintain uniform pressure for the temperature and current conditions through the clamping device, it is necessary to have a flexible element in the joint, and in this embodiment of our invention, this flexibility is provided by the clamping jaw member H1 which is, in effect, nothing more than a relatively stiff spring.

From the foregoing it should be obvious that we have provided novel forms of a fuse terminal clamp which a e designed not only for giving proper current conduction with high pressure electrical contacting portions, but are also de signed to take care of varying conditions which may be encountered, particularly with respect to temperatures so that the high pressure contact may be preserved. At the same time, we have provided a fuse terminal clamp which is relatively simple in form and economical to manufacture, yet being highly efiicient in practical operation.

Having described preferred embodiments of our invention, in accordance with the patent statutes, we wish it to be understood that our invention is not to be limited to the particular embodiments disclosed herein, inasmuch as it will be obvious, particularly to persons skilled in the art, that many changes and modifications may be made in these particular embodiments without departing from the broad spirit and scope of our invention. Therefore, we desire that our invention be interpreted as broadly as possible and that it be limited only by what is expressly stated in the following claims.

We claim as our invention:

1. In an electric terminal clamp, a pair of cooperating clamping jaws, one of which is provided with an aperture for loosely receiving an angular extension of said other jaw member for pivotally mounting said jaw members for movement toward and away from each other, and means cooperating with said one jaw and said extension for effecting said relative pivotal movement of said other jaw member.

2. In an electric terminal clamp, a pair of cooperating clamping jaws, one of which is provided with a base and an angularly related outstanding apertured jaw portion, the other of said jaws including a jaw portion, and an angularly related support portion extending through said aperture, means preventing withdrawal of said angular support portion from said aperture, and means cooperating with said support portions for causing relative movement of said jaw portions.

3. In an electric terminal clamp, a pair of cooperating clamping jaws one of which is of a low resistance good electrical conducting material, and the other of which is of a relatively stiif resilie t material, said one jaw being provided til 1 an aperture for loosely receiving an angular :tension of said other jaw member for pivctally mounting said jaw members for movementtoward and away from each other, and l eans cooperating with said one jaw and said extension for effecting said relative movement.

In an electric terminal clamp, a pair of cooperating clamping jaws one of which is of a low resistance good electrical conducting material, and Le other of which is solely of a relatively stifi resilient material having a higher electrical resistance, said jaws being mounted for relative movement into and out of position to clamp a fuse terminal therebetween, means cooperating with said jaws for effecting said rel"- tive movement and resilient reenforcing means for said one jaw.

5. In an electric terminal clamp, a pair of cooperating clamping jaws one of which is of a low resistance good electrical conducting material, and the other of which is solely of a relatively stiff resilient material having a greater q electrical resistance, said jaws being mounted for relative movement into and out of position to clamp a fuse terminal therebetween, means cooperating with said jaws for efiecting said relative movement and arranged so as to reenforce said one jaw.

6. In an electrical terminal clamp, a pair of cooperating clamping jaws one of which is of a low resistance good electrical conducting material, the other of which is of a relatively stiii resilient material, said one jaw having angular portions adjacent opposite ends thereof, and an aperture therebetween for movably receiving an angular extension of said other jaw, one of said angular portions constituting a support for said claimp, and means cooperating with the other of said angular portions and said extension for causing relative movement of said jaws.

'7. In an electrical terminal clamp, a base having a integral current-carrying apertured jaw p01 tion, an angular jaw member having one leg portion thereof extending through the aperture in said integral jaw portion to provide for movement of said jaw member to and from said jaw portion, and means cooperating with said base and said one leg portion for controlling said movement.

8. In an electrical terminal clamp, a base having an integral current-carrying apertured jaw portion, resilient backing means for said jaw portion, an angular jaw member having one leg portion thereof extending through the aperture in said integral jaw portion to provide for movement of said jaw member to and from said jaw portion, means for securing said base to a support :1, resilient backing means for said jaw porand extending into cooperative relation with respect to said one leg portion for controlling said jaw movement.

9. In an electrical terminal clamp, a base having an integral current-carrying apertured jaw portion, resilient backing means for said jaw portion, an angular jaw member having one leg portion thereof extending through the aperture in said integral jaw portion to provide for movement of said jaw member to and from said jaw portion, and means cooperating with said one leg portion and a portion of said jaw portion on the opposite side of said aperture from the base, for controlling said movement.

10. In an electrical terminal clamp, a pair of cooperating clamping jaws, one of which is provided with an aperture for loosely receiving an angular extension of said other jaw member for pivotally mounting said jaw members for movement toward and away from each other, means cooperating with said one jaw and said extension for eifecting said relative movement, and at least one of said jaws including means for preventing longitudinal endwise movement of a fuse terminal.

11. In an electrical terminal clamp, crossed jaw members one of which is provided with a base portion adapted to be mounted on a support, means pivotally associating said jaw members at the point where they cross, and means cooperating with one set of adjacent ends of said members for effecting relative pivotal movement of said members and cause the other ends of said members to move towards each other into clamping engagement with a terminal located therebetween.

12. In an electric terminal clamp, a pair of cooperating clamping jaws one of which is of a low resistance good electrical conducting material, and the other of which is solely of a relatively stifi resilient material having relatively greater electrical resistance, said jaws being mounted for relative movement into and out of position to clamp a fuse terminal therebetween, and means cooperating with said jaws for efiecting said relative movement.

13. In an electrical terminal clamp, a pair of cooperating clamping jaws, one of said jaws having angular portions adjacent opposite ends thereof, and an aperture therebetween for movably receiving an angular extension of the other of said jaws, one of said angular portions constituting a support for said clamp, and means coopcrating with the other of said angular portions and said extension for causing relative movement of said jaws.

14. In an electric terminal clamp, opposed members spaced apart to receive a fuse terminal therebetween, one of said members being solely of a low resistance good electrical conducting material, and the other of said members being solely of a relatively stiff resilient material having greater electrical resistance, and means cooperating with at least one of said members for forcing a fuse terminal into intimate engagement with said low resistance member while stressing the other of said members.

LAWRENCE PIERCE. JOHN W. SAMZELIUS. MARTIN WIBELL. 

